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Title: Self-similar random process and chaotic behavior in serrated flow of high entropy alloys

Here, the statistical and dynamic analyses of the serrated-flow behavior in the nanoindentation of a high-entropy alloy, Al 0.5CoCrCuFeNi, at various holding times and temperatures, are performed to reveal the hidden order associated with the seemingly-irregular intermittent flow. Two distinct types of dynamics are identified in the high-entropy alloy, which are based on the chaotic time-series, approximate entropy, fractal dimension, and Hurst exponent. The dynamic plastic behavior at both room temperature and 200 °C exhibits a positive Lyapunov exponent, suggesting that the underlying dynamics is chaotic. The fractal dimension of the indentation depth increases with the increase of temperature, and there is an inflection at the holding time of 10 s at the same temperature. A large fractal dimension suggests the concurrent nucleation of a large number of slip bands. In particular, for the indentation with the holding time of 10 s at room temperature, the slip process evolves as a self-similar random process with a weak negative correlation similar to a random walk.
Authors:
 [1] ;  [2] ;  [2] ;  [1] ;  [2] ;  [2] ;  [3] ;  [3] ;  [3] ;  [4] ;  [1]
  1. The Univ. of Tennessee, Knoxville, TN (United States)
  2. Zhengzhou Univ. (China)
  3. Univ. of Kentucky, Lexington, KY (United States)
  4. Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 6; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Fossil Energy (FE); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Scientific User Facilities Division; National Science Foundation (NSF); National Natural Science Foundation of China (NNSFC); U.S. Army Research Laboratory - U.S. Army Research Office (ARO)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; material science; mathematics and computing
OSTI Identifier:
1341016